In safety systems such as restraining systems operating on an electronic basis, the critical components, such as sensors, preprocessing circuits, and computers, and in particular, microcomputers for signal processing, may be provided in a redundant fashion, and in particular in duplicate. As a result of the redundancy provided, such known restraining systems provide increased safety. However, this is at the expense of high production costs since a relatively large number of components have to be produced.
If redundancy is omitted in known safety systems, i.e., the system components are simply present once, the costs are indeed lowered, but a lower safety level must then also be assumed. This results from the facts that inappropriate triggerings of the vehicle occupant safety system may not to be ruled out, and that a triggering of the safety system may not occur when it is required.
European No. 0 283 737 describes a circuit arrangement for actuating a protection system for vehicle occupants in which a safety system trigger is disposed in an airbag housing. A plurality of trigger switches are connected in series with one another and in series with the trigger 10, the switches being driven by current sources with are loaded themselves in turn by output signals from logic components. The output signals are fed as a function of the delay of switching double switches to input terminals of the logic components connected in parallel. The functions of the logic components can be taken over by correspondingly programmed microcomputers with corresponding peripherals. In the document, it is also pointed out that for test purposes in each case one part of the trigger switch can be periodically driven at particular intervals, it being also possible for this driving to be carried out by a microprocessor.